During a sorting process, the sorted postal items are stored in the sort-outlet trays, and when a sort-outlet tray is full, the full tray is replaced with an empty tray by means of an automatic tray change system that is, for example, part of an Automated Tray Handling System (ATHS).
While a full tray is being replaced with an empty tray, the corresponding sort outlet is unavailable for the sorted items, the time for which it is unavailable being approximately a few seconds (about 5 seconds). The overflow items that ought to have been directed to that sorting outlet while the full tray is being replaced must be recycled on the bin carousel.
Recycling said postal items uses up bins of the carrousel and is detrimental to the operating throughput of the sorting machine.
If postal items are recycled while postmen's walks are being prepared, that results in the order (sequence) of the items being lost, and such postal items must therefore be directed towards a reject outlet for manual sorting, which gives rise to considerable extra handling costs.
Techniques for overflow management of sort-outlet trays are already known that consist in providing two trays per sort outlet and in causing them to operate alternately. However, those techniques require a complicated tray handling system.